"Blah" (3)
I believe the answer is:
meh
'blah' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for meh that I've seen before include "am I bovvered?" , "Not much cop" , "Unexciting (modern slang)" , "expression of indifference" , "Who cares" .)